Lower respiratory tract infections are generally more serious than upper respiratory infections. LRIs are the leading cause of death among all infectious diseases.[2] The two most common LRIs are bronchitis and pneumonia.[3]Influenza affects both the upper and lower respiratory tracts, but more dangerous strains such as the highly pernicious H5N1 tend to bind to receptors deep in the lungs.[4]

A 2014 systematic review of clinical trials does not support using routine rapid viral testing to decrease antibiotic use for children in emergency departments.[5] It is unclear if rapid viral testing in the emergency department for children with acute febrile respiratory infections reduces the rates of antibiotic use, blood testing, or urine testing.[5] The relative risk reduction of chest x-ray utilization in children screened with rapid viral testing is 77% compared with controls.[5] In 2013 researchers developed a breath tester that can promptly diagnose lung infections.[6][7]